1. Field of the Invention
The present invention is related to distributing power to rack mounted electronic devices. More particularly, the present invention is related to routing direct current power to a plurality of rack-mounted computer systems in server operation. More particularly still, the preferred embodiments of the present invention are directed to grouping supply and return cables in DC power distribution systems into cable-end housings that insure correct placement of the cables as well as insure that the polarities are not reversed in the connection process.
2. Background of the Invention
As the size of computers becomes smaller, so too does the number of computers that may be placed in one particular place. For persons and entities providing server services, e.g., Internet service providers (ISPs) and corporate computer departments, smaller computer footprints allow a smaller required area, or more computers in the same areas already allocated.
Given that each server is effectively just an individual computer, each of these devices must have at least power cable and a cable to carry information to and from the server. In years past, when a single computer may have occupied an entire drawer in a rack-mounted system, having the necessary space for power and information cables was not of particular concern.
A backplane board is simply an electrical circuit board placed at substantially right angles to the insertion direction of rack-mounted server systems. In such a system, the act of pushing the computer into the rack physically couples the computer to the backplane board. In this way, digital signals and power may be coupled to the computer system. Further, use of the backplane board allows the rack-mounted computer system designer to move cable connections, if any, to more desirable locations.
Initial assembly of a server system, or re-assembly after repair, is generally a tedious process with respect to the connection of various electrical cables. In particular, it is a tedious and time-consuming process to trace each particular cable, and land that cable at its appropriate location, e.g., by way of a lug and screw or nut. Moreover, individually tracing and landing wires, especially power cables for DC supply systems, is prone to errors, e.g., reversing polarity on DC power supplies. Such a reversal can lead to catastrophic failure of many devices in the server system and of the individual computers of that server system. For example, consider a rack mounted server system having five chassis mounted within the rack, each chassis having a plurality of computers. Further consider that each chassis may have two connections to the power source, a primary connection and a redundant connection. If each connection involves a power supply cable and a power return cable, it is easily seen that, just on the power distribution side, 20 cables must be draped from point to point just to distribute the power. Reversing the polarity of connection in such a DC system may be catastrophic to the devices therein. Further, improperly connecting these cables may result in the redundant capability being inoperable.
Thus, what is needed in the art is a mechanism to distribute power in a rack-mounted server system that is easily connected and disconnected without the need of attaching individual cables. The system should advantageously group respective sets of power and return cables, should insure that an operator or technician will not connect that grouping of cables in a reverse polarity, and should minimize the effort required to connect and remove the cable groupings.
The problems noted above are solved in large part by a structure and related method which organizes the plurality of DC power distribution cables present in a typical rack-mounted server system. In particular, each pair of supply cables, a power supply cable and a power return cable, are grouped and have their respective chassis ends grouped into a cable-end housing. This cable-end housing preferably has two apertures and a back surface thereof that allows electrical access to the ends of the grouped power supply and power return cables. Preferably, each cable within the cable-end housing has a right-angle connector coupled thereto which has its aperture preferably aligned coaxially with the respective aperture in the back surface of the cable-end housing. On the chassis in the rack, preferably there exists a connection area having two electrically conductive pins mounted thereon and extending substantially perpendicularly to a plane formed by the connection area. These two pins are preferably sized and spaced such that when a cable-end housing is placed thereon, the pins slide through the apertures in the back surface of the cable-end housing and contact their respective right-angle connectors, which then couple the power through the connectors to the server.
A second aspect of the preferred embodiments is a connector guide preferably mounted on the connection area. The connector guide has a lip portion that extends substantially the same direction as the electrical contact pins. The combination of the placement of the apertures through the back surface of the cable-end housing, and the placement of the connection guide above the electrical pins of the connection area, insure that electrically coupling the cable-end housing to the electrical pins in the connection area cannot connect with the polarity reversed. More particularly, the apertures through the back surface of the cable-end housing are preferably placed in an upper half of the back surface a particular distance from the top of the cable-end housing. Relatedly, the connection guide is preferably placed a certain distance above the electrical contact pins of the connection area, and the certain distance that the connection guide is placed is slightly larger than the distance from the apertures in the cable-end housing to the top of the cable-end housing. In this way, the cable-end housing only fits on the electrical contact pins in one direction. If a technician or user attempts to install the cable-end housing upside down, the lip on the connection guide physically prevents proper seating of that electrical connection, thus insuring that an operator or technician will become aware of the potential problem.
Thus, the preferred embodiment addresses the problems of an abundance of power cables on the back of a rack-mounted server system by grouping related cables and insuring that those cables are not installed with reverse polarity.